Catheter-type instrument



June 7, 1949. KRIPPENDORF 2,472;485

CATHETER-TYPE INSTRUMENT Original Filed May 5, 1944 I a Zia 325%, j

INVENTOR. 10w; H. far/ emover Patented June 7, 1949 UNITED STATES PATENTOFFICE CATHETEB-TYPE INSTRUMENT Louis H. Krippendorf, White Plains, N.Y., as-

signor to American Catheter Corporation, Port Chester, N. Y., acorporation of New York 2 Claims.

This application is a division of my co-pending application, Serial No.534,207, filed May 5, 1944, now Patent No. 2,437,542.

The invention relates generally to surgical instruments and hasparticular reference to catheter-type instruments.

By the term catheter-type instrument, as used herein and in the appendedclaims, I intend to refer to the well-known kind of device which isinserted endwise into and through constricted body channels fordiagnostic, therapeutic and allied purposes. Illustrative of suchinstruments are ureteral and urethral catheters, bougies, filiforms andthe like.

A conventional instrument of this type is of elongated character and hasa uniform over-all flexibility coupled with suflicient rigidity topermit its endwise advancement. This paradoxical requirement for bothflexibility and rigidity has heretofore presented a peculiar problem tothe manufacturer. For example, in the case of a ureteral catheter, itmust be of sufficient flexibility to permit the tip of the instrument toadvance harmlessly through the constricted ureteral canal and readily tofollow the curvatures encountered, yet as the flexibility is increasedby the manufacturer to meet this requirement, the body portion losessome of the rigidity necessary to enable the operator to effect thedesired advancement by endwise pressure exerted upon the rear end of theinstrument. Similarly, in the case of bougies or the like, it may undercertain circumstances be desirable to increase the rigidity of the tipportion, yet the instrument as a whole may thereby become too inflexibleto follow an irregularly curved path with adequate ease.

The principal object of my present invention is directed toward asolution of this problem, and my invention is predicated upon thediscovery that a catheter-type instrument may be caused to embodydifferent flexibilities along its longitudinal axis without materiallyaltering its basic structural nature or impairing the other inherentqualities which it necessarily must possess. This desirable andadvantageous result is achieved in an entirely practical andcommercially-feasible manner.

In accordance with one conventional manufacturing procedure, theconstruction of a catheter-type instrument involves the formation of aninitially limp fabric base of interwined threads, this base beingusually first impregnated with a flexible stiffening medium and thencoated with a flexible varnish. In the practice of my present invention,this general procedure is ad- 2 hered to, yet the body portion of theresultant instrument may be caused to embody a flexibility in theforward or other section thereof which is to a predetermined extentappreciably greater or less than the flexibility in an adjacent section.

This new result and its corresponding advantages may be accomplished inthe manner illustratively exemplified in the accompanying drawings, inwhich:

Figure l is a perspective view of a typical catheter-type instrument.

Figure 2 is an enlarged fragmentary view of a portion of the instrumentwith the outer coating broken away to reveal the fabric base in theregion of the line AA of Figure l; and

Figure 3 is a diagrammatic view illustrating the comparativecharacteristics, as far as flexibility is concerned, of a conventionalcathetertype instrument and one which has been constructed in accordancewith the present invention.

The features of the invention may best be described by brief preliminaryreference to conventional practice.

A fabric base is first created. Usually, this base assumes the form ofan elongated hollow tube, but under certain circumstances it need nothave a longitudinal passageway extending through it. This base is formedof interwined threads of silk, cotton, or synthetic fibre, and usuallythe threads are braided into the desired relationship. Any weaving orother procedure may be restorted to, however, if desired, althoughbraiding machines have proven to be admirably suited to produce atubular or elongated fabric base of the character required. This base isinitially limp in character, and is customarily impregnated with aflexible stiffening medium of suitable composition. Where the base is atube, the impregnation is carried out While the tube is mounted upon asuitable rod or mandrel. After wiping off any excess, the mandrel (ifone has been used) is removed and the impregnating medium is caused toharden or cure, either by air drying, or by subjection to a bakingprocedure or the like. The reinforced and strengthened fabric base isthen subjected to a series of operations during which a flexible toughvarnish coating is applied to it, layer by layer, the successivecoatings being cured by baking or analogous procedures. After thedesired coating has been formed, it is burnished and the instrument issubjected to such other finishing processes as may be deemed desirable.

The forward tip of the instrument may be formed either prior to or afterthe initial impregnation of the fabric base, depending upon the natureof the instrument, and the kind and shape of tip which it is intended tohave. In the case of catheters, the several openings or eyes whichcharacterize these instruments may be formed at or near the forward tipeither during the braiding of the base or during a subsequent stage oftreatment.

Depending upon the nature and size of the threads originally employed informing the fabric base. upon the dimensions of this base and upon theimpregnating and coating media which are employed, the resultantinstrument will have a size and flexibility of predetermined character.Heretofore, in an instrument in which the body portion is ofsubstantially uniform diameter, the bendability and over-allsemi-rigidity has been uniform throughout, being usually determined by asuitable compromise between the flexibility required for any givenpurpose and the stiffness called for by the well-known method in whichthe-instrument is to be employed.

In accordance with my invention, the essential nature of themanufacturing process remains unchanged, yet varying degrees offlexibility may be imparted to the resultant instrument along itslongitudinal axis. For illustrative purposes, I have chosen to describeand illustrate the manner in which a catheter may be caused to have anappreciably increased flexibility in its forward region adjacent to thetip, as compared with the flexibility and rigidity of the remaining mainportion thereof.

Thus, in Figure 1, I have illustrated a catheter H] in which the regionforwardly of the dot-anddash line A has been caused to embody a greaterflexibility than the remaining main portion of thecatheter.

In the procedure followed in accordance with the present invention, theinitially limp fabric base tube 22 is impregnated with a flexiblestiffening medium, which may be, for example, of the general type inwhich a suitable carrier such as tung oil is associated with a resin orresins of J polymerizable type, together with a plasticizer or othercustomary ingredients. There are numerous resins which can be employed,and among them are, for example, resins of the phenolic type. Theplasticizer used may 'be any of the usualones, such as castor oil,dibutyl phthallate, tri-cresyl-phosphate, and the like.

In practice, the tube may be mounted on a suitable rod or mandrel (notshown) either before or after the forward tip is formed, and may then bedipped into the impregnating medium. The excess is then wiped off, therod or mandrel is withdrawn, and the impregnated tube may be placed in asuitable oven to bring about a curing of the impregnating medium.

Subsequently, the tube is handled to form on it the outer coating 23 offlexible varnish, which may be composed, for example, of a tung oilbase, a phenolic or other suitable resin, and a plasticizer. By curingthis coating to a greater extent in one section than in alongitudinally-adjacent section. the desired different fiexibilities canbe imparted to the corresponding sections of the instrument. Forexample, in producing a catheter having the characteristics shown inFigure 1, the normal and conventional procedure may be followedthroughout, and the rearward part of the instrument may then besubjected to an additional baking or curing whereby a greater rigidityis, imparted to it. In Practice, this ,maybe accomplished by dipping theforward region (up to the line A-A, for example) in a suitable 011 orother liquid while the entire instrument is subjected to a bakingtemperature.

The outer coating 23 is a tough and ,flexlble film having a smoothglossy surfacaand resistant to water, body fluids generally, andstandard types of sterilization.

The basic difference between the instrument of Figure 1 and the ordinarytype of instrument is indicated diagrammatically in Figure 3. If theordinary catheter I8 is pressed endwise against an abutment wall i9, bypressure exerted in the direction indicated by the arrow 20, it willbuckle throughout its length. On the other hand, if the instrument I0 ofFigure 1 is similarly pressed against an abutment 19 by a similarpressure exerted along the direction of the arrow 2|, it will buckle inthe formed region of greater flexibility, but not otherwise.Accordingly, when the instrument It! is inserted into and advancedthrough one of the ureters or through anyother' similar constricted bodycanal, it will feel its was: more easily past the curvaturesencountered, .and this makes the operation safer and simpler.

llhile I have illustrated a catheter, it will be understood that theinvention is equally-applicable to any catheter-type instrument, whetherhollow or not; and while I have chosentoillus trate the manner in whichthe forward region of the instrument may be made more flexible: than thebalance, it will be understood that other. relative fiexibilities may beproduced, depending upon particular requirements.

In general it will be understood that thedetalls herein described andillustrated to explain the. general nature and objective of theinvention. may readily be modified by those skilled in the. art withoutdeparting from the spirit and-,SQOI-lfi. of the invention as expressedin the appended. claims.

Having thus described my inventionand illus trated its use, what I claimas new and desire:

to secure by Letters Patent is:

1. In an elongated flexible catheter-type 1nstrument, an initially limpfabric base ,impreg. natecl with a flexible stiffening medium. and:coated with a flexible varnish, the varnishwhlch. coats one region ofsaid base being of appreciably greater flexibility than that which coatsa longie tudinally-adjacent region thereof, the fiexibilities. of thecorresponding sections of the instrument. being correspondinglyaffected.

2. In an elongated flexible catheter-type .inestrument, an initiallylimp fabric base impregnated with a flexible stiffening medium and.coated with a flexible cured varnish, the varnish which coats one regionof said base being cured, to a lesser extent than that which coatsalongltudinally-adjacent region thereof, the lessercured coating beingof appreciably greater fiexibility than the other and theflexibilitiesofithm corresponding sections of the instrument being.correspondingly affected.

LOUIS H. KRIPPENDQRE.

REFERENCES CITED The following references are of record ln-the file ofthis patent:

UNITED STATES PATENTS Number Name Date 757,877 Bosch .Apr..19, 191)..,776,879 Baekeland Sept. .30, 193.0. 2,437,542 Krippendorf Mar- 9,1958.

